The present invention relates to printing systems and methods for printing with the same. More particularly, the present invention relates to printing systems with cartridges that are configured to radially print onto a media that rotates in relation to a printing assembly.
Conventional printing systems typically utilize rectangular based bitmaps. In general, a conventional printing system prints onto a standard size rectangular-shaped media along a horizontal axis, for example, and the media is moved along a vertical axis. Typically, after the paper advances to a desired vertical location under a head assembly, the printing assembly moves across the paper to print an image onto the paper while the paper is held stationary. In sum, conventional printing systems generally implement movements within a rectangular coordinate system for printing onto media having standard sizes and shapes.
To facilitate discussion, FIG. 1 depicts a conventional printing system 10 in the form of a typical ink jet printer. As shown, the printing system 10 includes a print head 102, a roller 106, an actuator 108, and an ink head service and capping area 120. The print head 102 is configured for dispensing ink onto a print media 100, representing, for example, a rectangular sheet of paper. The actuator 108 is configured for moving the print head 102 across the print media 100. The roller 106 is configured for moving the print media 100 under the print head 102.
Typically, the roller 106 moves the print media 100 perpendicularly to the movement of the print head 102. That is, the media 100 travels under the print head 102 along a y-axis 110, and the print head moves over the media 100 along an x-axis 112. Periodically to service the ink jet nozzles, the print head 102 is moved past the paper edge along an x-axis to the service station 120, where it clears, wipes 126 and caps 124 the nozzles.
Although conventional printing systems such as those described above are suitable for certain applications, they also have certain disadvantages. The print head cartridge in conventional ink jet printers, for example, as disclosed in U.S. Pat. No. 4,872,026, are typically optimized for printing rectangular objects like paper using x-y axis coordinate system printers, and are inherently not optimized for printing along radial axis.
FIG. 2 illustrates a radial print system 200, as disclosed in U.S. Pat. No. 6,264,295, issued Jul. 24, 2001. In the radial printing system 200, the head assemble 210 in one embodiment of this invention consists of a conventional ink jet cartridge that also has print head 102 that moves radially and tangentially to the spinning media underneath in contrast to the conventional printing system 10 of FIG. 1, which moves print head 102 in the x-axis direction across the media 100 under print while the media 100 gradually advances along the y-axis. Where on the one hand, the spatial resolution of the ink object resolution is normally constant across the conventional printing system 10 media, on the other hand, the spatial resolution of the radial print system printing ink objects increases as the radial position of the ink jet cartridge increases with respect to the circular CD-R media.
The ink jet cartridges designed for use in conventional printing system are inherently not optimized to place ink object for radial printing. FIGS. 3a and 3b illustrate the bottom view of a conventional cartridge 300 that has nozzles 320 with orientation, firing order, and firing rates optimized for rectangular printing in the orthogonal or Cartesian reference coordinate system. However, this same cartridge print head and nozzles produce non-optimal results when used to print radially in the polar reference coordinate system. For example, in a conventional printing system cartridge 300, nozzles 320 are usually arranged along a parallel vertical lines offset 334 from the centerline 330 of the print head 310. While this design may be optimal for rectangular printing, in contrast during radial printing this orientation causes distortion due in part to the misalignment of the nozzle axes 320 relative to the radial centerline 330. To partially correct for this, the each respective nozzle axis, 320a and 320b, must be laterally translated in motion an offset distance 334 so as to be centered over the radial centerline 330 prior to printing. This extra translation requirement causes extra steps to be added to the radial printing system operation and reduces overall print speed and performance.
Another limitation associated with using conventional rectangular-optimized cartridges 300 in the radial print system 200 is the way conventional print head nozzles 320 are designed to operate. In conventional printer operations, the firing order of each nozzle is typically addressed electronically using a grid-like, row-column technique, to more easily enable the nozzles in conventional cartridges to fire at the appropriate time optimized for the rectangular media printing environment or to simplify the electronics interface. Since the conventional print head nozzles 320 are typically arranged to be fired optimally in column order instead of azimuthal 340 or radial order, printing is inherently slower for radial printing and print speed diminishes due to missed printing opportunities. For example, because conventional cartridge nozzles 310 usually are fired in column order, the target zone where to place an ink object may pass by before the next addressed nozzle is ready to fire, necessitating the target to pass repeatedly underneath the print head nozzles 320. In this case until it is ready to fire, the print head 310 must linger over the spinning media, awaiting the target zone for a much longer period of time than is optimal in order to ensure complete ink object coverage. Another aspect of these design limitations of conventional print heads 310 causes the column addressing modes to constrain and restrict the firing order during radial printing operation, to the extent that the next radial dot position is missed, because the firing order cannot be configured flexibly enough or fast enough to allow for optimal azimuthal 340 print coverage.
Yet another disadvantage of ink jet cartridges 300 used in conventional rectangular printers is that their vertical height is too tall for particular printing applications. Conventional ink jet cartridges are usually not designed to limit physical height, but rather are so designed to be as tall as practical for larger ink reservoir capacity.
Another disadvantage of conventional printing systems using ink jet technology is the necessity for a separate print head service device. Referring back to FIG. 1, the conventional design of a print head 102 necessitates it being serviced frequently to maintain optimal performance of the print head, so a separate service station 120 is required to wipe 126 and clear the print head 102 nozzles during printing and cap 124 the print head for storage while not in use. This service station is often a separate device 120 inline with the x-axis 112 direction of the print head 102 movement, beyond the placement of the media 100. However, for a radial print system, a separate service station may occupy substantial portions of the space available in a radial printing system. In addition, a separate service station 120 can inherently slow down printing due to the need to add extra motion steps outside the normal radial positioning motion during the radial printing operations.
In view of the foregoing, there is a need for an improved printing system cartridge for radial printing that efficiently implements simple movements, inherently reduces distortion while minimizing the amount of space taken by such cartridge within a radial printing system.